Tidy Text Notebook

By David Robinson and Julia Silge

This is my notebook that I will used to go through the tidy text notebook by Julia Silge and David Robinson.

library(tidyverse)
library(tidytext)
library(stringr)
library(janeaustenr)
text <- c("Because I could not stop for Death - ", 
          "He kindly stopped for me -",
          "The Carriage held but just Ourselves -",
          "and Immortality")
text

[1] "Because I could not stop for Death - "  "He kindly stopped for me -"             "The Carriage held but just Ourselves -" "and Immortality"                       

text_df <- data_frame(line = 1:4, text = text)
text_df

text_df %>% 
  unnest_tokens(word, text)  # to_lower = FALSE to keep uppercase

Working with Jane Austen Books

Using the Jane Austen dataset we can make it tidy. First we’ll use mutate to create a column from existing data. Annotate line numbers and then keep track of chapters using regex.

original_books <- austen_books() %>% 
  group_by(book) %>% 
  mutate(linenumber = row_number(),
         chapter = cumsum(str_detect(text, regex("^chapter [\\divxlc]",
                                                  ignore.case = TRUE)))) %>% 
  ungroup()
original_books

Restructure it in one-token-per-row format with the unnest_tokens() function.

tidy_books <- original_books %>% 
  unnest_tokens(word, text)
tidy_books

Removing stop words

We can remove stop words

data(stop_words)
tidy_books <- tidy_books %>% 
  anti_join(stop_words)

Joining, by = "word"

tidy_books %>% 
  count(word, sort = TRUE)

Plotting data

tidy_books %>% 
  count(word, sort = TRUE) %>% 
  filter(n > 600) %>% 
  mutate(word = reorder(word, n)) %>% 
  ggplot(aes(word, n))+
  geom_col()+
  xlab(NULL)+
  coord_flip()+
  theme_bw()

Gutenbergr

HG wells books

library(gutenbergr)
hgwells <-  gutenberg_download(c(35, 36, 5230, 159))

Determining mirror for Project Gutenberg from http://www.gutenberg.org/robot/harvest
Using mirror http://aleph.gutenberg.org

tidy_hgwells <- hgwells %>% 
  unnest_tokens(word, text) %>% 
  anti_join(stop_words)

Joining, by = "word"

tidy_hgwells %>% 
  count(word, sort = TRUE)

Most commone words in novels by Bronte sisters

bronte <-  gutenberg_download(c(1260, 768, 969, 9182, 767))
tidy_bronte <- bronte %>% 
  unnest_tokens(word, text) %>% 
  anti_join(stop_words)

Joining, by = "word"

tidy_bronte %>% 
  count(word, sort = TRUE)

Comparing Bronte and HG Wells

frequency <- bind_rows(mutate(tidy_bronte, author = "Bronte Sisters"),
                       mutate(tidy_hgwells, author = "H.G. Wells"),
                       mutate(tidy_books, author = "Jane Austen")) %>% 
  mutate(word = str_extract(word, "[a-z']+")) %>% 
  count(author, word) %>% 
  group_by(author) %>% 
  mutate(proportion = n / sum(n)) %>% 
  select(-n) %>% 
  spread(author, proportion) %>% 
  gather(author, proportion, `Bronte Sisters`:`H.G. Wells`)

Graphing the comparisons

library(scales)

Attaching package: ‘scales’

The following object is masked from ‘package:purrr’:

    discard

The following object is masked from ‘package:readr’:

    col_factor

ggplot(frequency, aes(x = proportion, y = `Jane Austen`,
                      color = abs(`Jane Austen` - proportion))) +
  geom_abline(color = "gray40", lty = 2) +
  geom_jitter(alpha = 0.1, size = 2.5, width = 0.3, height = 0.3) +
  geom_text(aes(label = word, check_overlap = TRUE, vjust = 1.5))+
  scale_x_log10(labels = percent_format()) +
  scale_y_log10(labels = percent_format()) +
  scale_color_gradient(limits = c(0,0.001),
                       low = "darkslategray4", high = "gray75") +
  facet_wrap(~author, ncol = 2) +
  theme(legend.position = "none") +
  labs(y = "Jane Austen", x = NULL)

Ignoring unknown aesthetics: check_overlap

NA

Correlation analysis

cor.test(data = frequency[frequency$author == "Bronte Sisters",],
         ~ proportion + `Jane Austen`)

    Pearson's product-moment correlation

data:  proportion and Jane Austen
t = 119.65, df = 10404, p-value < 2.2e-16
alternative hypothesis: true correlation is not equal to 0
95 percent confidence interval:
 0.7527846 0.7689620
sample estimates:
      cor 
0.7609915 

cor.test(data = frequency[frequency$author == "H.G. Wells",],
         ~ proportion + `Jane Austen`)

    Pearson's product-moment correlation

data:  proportion and Jane Austen
t = 36.441, df = 6053, p-value < 2.2e-16
alternative hypothesis: true correlation is not equal to 0
95 percent confidence interval:
 0.4032800 0.4445987
sample estimates:
      cor 
0.4241601 

Sentiments dataset

library(tidytext)
sentiments

Sentiment scores

# AFINN
get_sentiments("afinn")

# Bing
get_sentiments("bing")

# NRC
get_sentiments("nrc")

Sentiment analysis can be performed with an inner join

tidy_books <- austen_books() %>% 
  group_by(book) %>% 
  mutate(linenumber = row_number(),
         chapter = cumsum(str_detect(text, regex("^chapter [\\divxlc]",
                                                 ignore_case = TRUE)))) %>% 
  ungroup() %>% 
  unnest_tokens(word, text)
tidy_books

Get a list of words that are associated with ‘joy’ and perform an inner_join to find words that are have ‘joy’ sentiment within Jane Austen’s Emma book.

# Filter words associated with 'joy'
nrcjoy <- get_sentiments("nrc") %>% 
  filter(sentiment == "joy")
# Find words associated with joy in Emma
tidy_books %>% 
  filter(book == "Emma") %>% 
  inner_join(nrcjoy) %>% 
  count(word, sort = TRUE)

Joining, by = "word"

Count up positive or negative words that are within sections of each book. We will define an index to keep track of where we are in the narrative. The index will count up sections of 80 lines of text

janeaustensentiment <- tidy_books %>% 
  inner_join(get_sentiments("bing")) %>% 
  count(book, index = linenumber %/% 80, sentiment) %>% 
  spread(sentiment, n, fill =0) %>% 
  mutate(sentiment = positive - negative)

Joining, by = "word"

janeaustensentiment

ggplot(janeaustensentiment, aes(index, sentiment, fill = book)) +
  geom_col(show.legend = FALSE) +
  facet_wrap(~book, ncol = 2, scales = "free_x")

pride_prejudice <- tidy_books %>% 
  filter(book == "Pride & Prejudice")
pride_prejudice

afinn <- pride_prejudice %>% 
  inner_join(get_sentiments("afinn")) %>% 
  group_by(index = linenumber %/% 80) %>% 
  summarise(sentiment = sum(score)) %>% 
  mutate(method = "AFINN")

Joining, by = "word"

afinn

bing_and_nrc <- bind_rows(
  pride_prejudice %>% 
    inner_join(get_sentiments("bing")) %>% 
    mutate(method = "Bing et al."),
  pride_prejudice %>% 
    inner_join(get_sentiments("nrc") %>% 
                 filter(sentiment %in% c("positive",
                                         "negative"))) %>% 
    mutate(method = "NRC")) %>% 
    count(method, index = linenumber %/% 80, sentiment) %>% 
    spread(sentiment, n, fill = 0) %>% 
    mutate(sentiment = positive - negative)

Joining, by = "word"
Joining, by = "word"

bing_and_nrc

Comparing three sentiment lexicons using Pride and Prejudice

bind_rows(afinn,
          bing_and_nrc) %>% 
  ggplot(aes(index, sentiment, fill = method)) +
    geom_col(show.legend = FALSE) +
    facet_wrap(~method, ncol = 1 , scales = "free_y")

get_sentiments("nrc") %>% 
  filter(sentiment %in% c("positive",
                          "negative")) %>% 
  count(sentiment)

get_sentiments("bing") %>% 
  count(sentiment)

bing_words_counts <- tidy_books %>% 
  inner_join(get_sentiments("bing")) %>% 
  count(word, sentiment, sort = TRUE) %>% 
  ungroup()

Joining, by = "word"

bing_words_counts

bing_words_counts %>% 
  group_by(sentiment) %>% 
  top_n(10) %>% 
  ungroup() %>% 
  mutate(word = reorder(word, n)) %>% 
  ggplot(aes(word, n, fill = sentiment)) +
  geom_col(show.legend = FALSE)+
  facet_wrap(~sentiment, scales = "free_y") +
  labs(y = "Contribution to sentiment",
       x = NULL,
       title = "Top 10 words by Sentiment for Pride and Prejudice") +
  coord_flip()

Selecting by n

Miss is referred to as a negative word but is not in Jane Austen’s works.

custom_stop_words <- bind_rows(data_frame(word = c("miss"),
                                          lexicon = c("custom")),
                               stop_words)
custom_stop_words

Wordclouds

library(wordcloud)

Loading required package: RColorBrewer

tidy_books %>% 
  anti_join(stop_words) %>% 
  count(word) %>% 
  with(wordcloud(word, n, max.words = 100))

Joining, by = "word"

library(reshape2)

Attaching package: ‘reshape2’

The following object is masked from ‘package:tidyr’:

    smiths

tidy_books %>% 
  inner_join(get_sentiments("bing")) %>% 
  count(word, sentiment, sort = TRUE) %>% 
  acast(word~sentiment, value.car = "n", fill = 0) %>% 
  comparison.cloud(colors = c("gray20", "gray80"),
                   max.words = 100)

Joining, by = "word"
Using n as value column: use value.var to override.

Looking at Units Beyond Just Words

PandP_sentences <-  data_frame(text = prideprejudice) %>% 
  unnest_tokens(sentence, text, token = "sentences")

PandP_sentences$sentence[2]

[1] "however little known the feelings or views of such a man may be on his first entering a neighbourhood, this truth is so well fixed in the minds of the surrounding families, that he is considered the rightful property of some one or other of their daughters."

Figuring out how many chapters are in a book

austen_chapters <- austen_books() %>% 
  group_by(book) %>% 
  unnest_tokens(chapter, text , token = "regex",
                pattern = "Chapter|CHAPTER [\\dIVXLC]") %>% 
  ungroup()
austen_chapters %>% 
  group_by(book) %>% 
  summarise(chapters = n())

bingnegative <- get_sentiments("bing") %>% 
  filter(sentiment == "negative")
wordcounts <- tidy_books %>% 
  group_by(book, chapter) %>% 
  summarize(words = n())
tidy_books %>% 
  semi_join(bingnegative) %>% 
  group_by(book, chapter) %>% 
  summarize(negativewords = n()) %>% 
  left_join(wordcounts, by = c("book", "chapter")) %>% 
  mutate(ratio = negativewords/words) %>% 
  filter(chapter !=0) %>% 
  top_n(1) %>% 
  ungroup()

Joining, by = "word"
Selecting by ratio

# Chapter 3

Term Frequency in Jane Austen’s Novels

book_words <- austen_books() %>% 
  unnest_tokens(word,text) %>% 
  count(book,word,sort = TRUE) %>% 
  ungroup()
total_words <- book_words %>% 
  group_by(book) %>% 
  summarize(total = sum(n))
book_words <- left_join(book_words, total_words)

Joining, by = "book"

book_words

Term frequency distribution in Jane Austen’s novels

ggplot(book_words, aes(n/total, fill = book)) +
  geom_histogram(show.legend = FALSE) +
  xlim(NA, 0.0009) +
  facet_wrap(~book, ncol = 2, scales = "free_y")

NA

Zipf’s Law

Zipf’s Law: frequency that a word appears is inversely proportional to its rank.

freq_by_rank <- book_words %>% 
  group_by(book) %>% 
  mutate(rank = row_number(),
         'term frequency' = n/total)
freq_by_rank

Graph of Zipf’s law for Jane Austen’s novels

freq_by_rank %>% 
  ggplot(aes(rank, `term frequency`, color = book)) +
  geom_line(size = 1.1, alpha = 0.8, show.legend = TRUE) +
  scale_x_log10() +
  scale_y_log10()

rank_subset <-  freq_by_rank %>% 
  filter(rank <500,
         rank >10)
lm(log10(`term frequency`) ~ log10(rank), data = rank_subset)

Call:
lm(formula = log10(`term frequency`) ~ log10(rank), data = rank_subset)

Coefficients:
(Intercept)  log10(rank)  
    -0.6226      -1.1125  

freq_by_rank %>% 
  ggplot(aes(rank, `term frequency`, color = book))+
  geom_abline(intercept = -0.62, slope = -1.1, color = "gray50", linetype = 2) +
  geom_line(size = 1.1, alpha = 0.8, show.legend = FALSE) +
  scale_x_log10() +
  scale_y_log10()

The bind_tf_idf Function

book_words <- book_words %>% 
  bind_tf_idf(word, book, n)
book_words

book_words %>% 
  select(-total) %>% 
  arrange(desc(tf_idf))

book_words %>% 
  arrange(desc(tf_idf)) %>% 
  mutate(word = factor(word, levels = rev(unique(word)))) %>% 
  group_by(book) %>% 
  top_n(15) %>% 
  ungroup() %>% 
  ggplot(aes(word, tf_idf, fill = book)) +
  geom_col(show.legend = FALSE) +
  labs(x = NULL, y = "tf-idf") +
  facet_wrap(~book, ncol = 2,scales = "free") +
  coord_flip()

Selecting by tf_idf

A corpus of Physics Text

physics <- gutenberg_download(c(37729, 14725, 13476, 5001),
                              meta_fields = "author")

physics_words <- physics %>% 
  unnest_tokens(word, text) %>% 
  count(author, word, sort = TRUE) %>% 
  ungroup()
physics_words

author_order <- c("Galilei, Galileo", "Huygens, Christiaan", "Tesla, Nikola", "Einstein, Albert")
plot_physics <- physics_words %>% 
  bind_tf_idf(word, author, n) %>% 
  arrange(desc(tf_idf)) %>% 
  mutate(word = factor(word, levels = rev(unique(word)))) %>% 
  mutate(author = factor(author, levels = author_order))
plot_physics

plot_physics %>% 
  group_by(author) %>%
  top_n(15, tf_idf) %>% 
  ungroup() %>% 
  mutate(word = reorder(word, tf_idf)) %>% 
  ggplot(aes(word, tf_idf, fill = author)) +
  geom_col(show.legend = FALSE) +
  labs(x = NULL, y = "tf-idf") +
  facet_wrap(~author, ncol = 2, scales = "free") +
  coord_flip()

NA

Isolating “eq” from Einstein’s text

physics %>% 
  filter(str_detect(text, "eq\\.")) %>% 
  select(text)

K1 was used for the coordinate system for Einstein

physics %>%
  filter(str_detect(text, "K1")) %>% 
  select(text)

NA

physics %>%
  filter(str_detect(text, "AK")) %>% 
  select(text)

mystopwords <- data_frame(word = c("eq","co","rc","ac","ak","bn",
                                   "fig", "file", "cg", "cb", "cm"))
physics_words <- anti_join(physics_words, mystopwords, by = "word")
plot_physics <- physics_words %>% 
  bind_tf_idf(word, author, n) %>% 
  arrange(desc(tf_idf)) %>% 
  mutate(word = factor(word, levels = rev(unique(word)))) %>% 
  group_by(author) %>% 
  top_n(15, tf_idf) %>% 
  ungroup() %>% 
  mutate(author = factor(author, levels = author_order))
plot_physics

ggplot(plot_physics, aes(word, tf_idf, fill = author)) +
  geom_col(show.legend = FALSE) +
  labs( x = NULL, y = "tf-idf") +
  facet_wrap(~author, ncol = 2, scales = "free") +
  coord_flip()

Chapter 4 Relationships Between Words: N-grams and Correlations

austen_bigrams <- austen_books() %>% 
  unnest_tokens(bigram, text, token = "ngrams", n = 2)
austen_bigrams

Counting and Filtering N-grams

austen_bigrams %>% 
  count(bigram, sort = TRUE)

bigrams_separated <-  austen_bigrams %>% 
  separate(bigram, into = c("word1", "word2"), sep = " ")
  
bigrams_filtered <- bigrams_separated %>% 
  filter(!word1 %in% stop_words$word) %>% 
  filter(!word2 %in% stop_words$word)
bigram_counts <- bigrams_filtered %>% 
  count(word1, word2, sort = TRUE)
bigram_counts

bigrams_united <- bigrams_filtered %>% 
  unite(bigram, word1, word2, sep = " ")
bigrams_united

austen_books() %>% 
  unnest_tokens(trigram, text, token = "ngrams", n = 3) %>% 
  separate(trigram, into = c("word1", "word2", "word3"), sep = " ") %>% 
  filter(!word1 %in% stop_words$word,
         !word2 %in% stop_words$word,
         !word3 %in% stop_words$word) %>% 
  count(word1, word2, word3, sort = TRUE)

Analyzing Bigrams

Identifying the “streets” in each book.

bigrams_filtered %>% 
  filter(word2 == "street") %>% 
  count(book, word1, sort = TRUE)

bigram_tf_idf <- bigrams_united %>% 
  count(book, bigram) %>% 
  bind_tf_idf(bigram, book, n) %>% 
  arrange(desc(tf_idf))
bigram_tf_idf 

The 12 bigrams with the highest tf-idf from each Jane Austen novel.

bigram_tf_idf %>% 
  arrange(desc(tf_idf)) %>% 
  mutate(bigram = factor(bigram, levels = rev(unique(bigram)))) %>% 
  group_by(book) %>% 
  top_n(12,tf_idf) %>% 
  ungroup() %>% 
  ggplot(aes(x = bigram, y = tf_idf, fill = book))+
    geom_col(show.legend = FALSE) +
    facet_wrap(~book, ncol = 2, scales = "free")+
    coord_flip()

Using Bigrams to Provide Context in Sentiment Analysis

bigrams_separated %>% 
  filter(word1 == "not") %>% 
  count(word1, word2, sort = TRUE)

AFINN <- get_sentiments("afinn") 
AFINN

not_words <- bigrams_separated %>% 
  rename(word = word2) %>% 
  filter(word1 == "not") %>% 
  inner_join(AFINN) %>% 
  count(word, score, sort = TRUE) %>% 
  ungroup()

Joining, by = "word"

    
    
not_words

NA

The 20 sords followed by “not” that had the greatest contribution to sentiment scores, in either a postivie or negative direction.

not_words %>% 
  mutate(contribution = n * score) %>% 
  arrange(desc(abs(contribution))) %>% 
  head(20) %>% 
  mutate(word = reorder(word, contribution)) %>% 
  ggplot(aes(word, n * score, fill = n * score > 0)) +
  geom_col(show.legend = FALSE) +
  xlab("Words preceded by \"not\"") +
  ylab("Sentiment score * number of occurences") +
  coord_flip()

negation_words <- c("not", "no", "never", "without")
negated_words <- bigrams_separated %>% 
  filter(word1 %in% negation_words) %>% 
  inner_join(AFINN, by = c(word2 = "word")) %>% 
  count(word1, word2, sort = TRUE) %>% 
  ungroup()
negated_words %>% 
  inner_join(not_words) %>% 
  mutate(contribution = n * score) %>% 
  arrange(desc(abs(contribution))) %>% 
  head(12) %>% 
  mutate(word = reorder(word, contribution)) %>% 
  ggplot(aes(word, n * score, fill = n * score > 0)) +
  geom_col(show.legend = FALSE) +
  xlab("Words preceded by \"not\"") +
  ylab("Sentiment score * number of occurences") +
  coord_flip() +
  facet_wrap(~word1)

Joining, by = "n"

Analyzing networks with igraph.

Create an igraph object from tidy data using the ‘graph_from_data_frame()’ function, which takes a data frame of edges with columns for “from”, “to” and edge attributes (in this case n).

library(igraph)

Attaching package: ‘igraph’

The following objects are masked from ‘package:dplyr’:

    as_data_frame, groups, union

The following objects are masked from ‘package:purrr’:

    compose, simplify

The following object is masked from ‘package:tidyr’:

    crossing

The following object is masked from ‘package:tibble’:

    as_data_frame

The following objects are masked from ‘package:stats’:

    decompose, spectrum

The following object is masked from ‘package:base’:

    union

bigram_counts

bigram_graph <- bigram_counts %>% 
  filter(n > 20) %>% 
  graph_from_data_frame()
bigram_graph

IGRAPH ff05f93 DN-- 91 77 -- 
+ attr: name (v/c), n (e/n)
+ edges from ff05f93 (vertex names):
 [1] sir      ->thomas      miss     ->crawford    captain  ->wentworth   miss     ->woodhouse   frank    ->churchill   lady     ->russell     lady     ->bertram    
 [8] sir      ->walter      miss     ->fairfax     colonel  ->brandon     miss     ->bates       lady     ->catherine   sir      ->john        jane     ->fairfax    
[15] miss     ->tilney      lady     ->middleton   miss     ->bingley     thousand ->pounds      miss     ->dashwood    miss     ->bennet      john     ->knightley  
[22] miss     ->morland     captain  ->benwick     dear     ->miss        miss     ->smith       miss     ->crawford's  henry    ->crawford    miss     ->elliot     
[29] dr       ->grant       miss     ->bertram     sir      ->thomas's    ten      ->minutes     miss     ->price       miss     ->taylor      sir      ->william    
[36] john     ->dashwood    de       ->bourgh      dear     ->sir         dear     ->fanny       miss     ->darcy       mansfield->park        captain  ->harville   
[43] charles  ->hayter      dear     ->emma        maple    ->grove       lady     ->russell's   miss     ->steeles     cried    ->emma        half     ->hour       
[50] harriet  ->smith       miss     ->steele      robert   ->martin      short    ->time        captain  ->wentworth's colonel  ->forster     miss     ->bertrams   
+ ... omitted several edges

Commone bigrams in Pride and Prejudice, showing those that occurred more thatn 20 times and where neighter word was a stop word

library(ggraph)
set.seed(2017)
ggraph(bigram_graph, layout = "fr") +
  geom_edge_link() +
  geom_node_point() +
  geom_node_text(aes(label = name), vjust = 1, hjust = 1)

Common bigrams in Pride and Prejudice, with some polishing

set.seed(2016)
a <- grid::arrow(type = "closed", length = unit(.15, "inches"))
ggraph(bigram_graph, layout = "fr") +
  geom_edge_link(aes(edge_alpha = n), show.legend = FALSE,
                 arrow = a, end_cap = circle(.07, 'inches')) +
  geom_node_point(color = "lightblue", size = 5) +
  geom_node_text(aes(label = name), vjust = 1, hjust = 1) +
  theme_void()

Topicmodels package

library(tm)
data("AssociatedPress", package = "topicmodels")
AssociatedPress

<<DocumentTermMatrix (documents: 2246, terms: 10473)>>
Non-/sparse entries: 302031/23220327
Sparsity           : 99%
Maximal term length: 18
Weighting          : term frequency (tf)

terms <- Terms(AssociatedPress)
head(terms)

[1] "aaron"      "abandon"    "abandoned"  "abandoning" "abbott"     "abboud"    

# library(tidyverse)
# library(tidytext)
ap_td <- tidy(AssociatedPress)
ap_td

ap_sentiments <- ap_td %>% 
  inner_join(get_sentiments("bing"), by = c( term = "word"))
ap_sentiments

# ggplot2
ap_sentiments %>% 
  count(sentiment, term, wt = count) %>% 
  ungroup() %>% 
  filter(n>= 200) %>% 
  mutate(n = ifelse(sentiment == "negative", -n, n)) %>% 
  mutate(term = reorder(term, n)) %>% 
  ggplot(aes(term, n, fill = sentiment)) +
  geom_col() +
  ylab("Contribution to sentiment") +
  coord_flip()

library(methods)
data("data_corpus_inaugural", package = "quanteda")
inaug_dfm <- quanteda::dfm(data_corpus_inaugural, verbose = FALSE)
inaug_dfm

Document-feature matrix of: 58 documents, 9,357 features (91.8% sparse).

inaug_td <- tidy(inaug_dfm)
inaug_td

inaug_tf_idf <- inaug_td %>%
  bind_tf_idf(term, document, count) %>% 
  arrange(desc(tf_idf))
inaug_tf_idf

NA

inaug_tf_idf %>% 
  filter(document %in% c("1861-Lincoln", "1933-Roosevelt", "1961-Kennedy", "2009-Obama")) %>% 
  ggplot(aes(reorder(term,tf_idf), tf_idf, fill = tf_idf)) +
  geom_col()+
  coord_flip()+
  facet_wrap(~document)